Parshas Bo opens as the eighth plague hits Egypt: a thick swarm of locusts devour the Egyptian crops.  Pharaoh begs Moses to remove the locusts and promises to free the Jews as soon as he complies.  Moses asks G-d to remove the plague - but when the locusts are gone, Pharaoh reneges on his agreement.  The ninth plague arrives and envelops the land of Egypt in darkness.  When the plague ends, Pharaoh remains adamant in his refusal to release the Jewish People.  G-d instructs Moses to warn Pharaoh about the upcoming tenth plague, in which each and every firstborn Egyptian male will die. 

The narrative is interrupted as Moses teaches the Jews a number of important laws.  The laws of Rosh Chodesh (exactly when to begin a lunar month) are taught, as well as the laws of the Korban Pesach (Passover offering) and the Passover holiday. 

As promised, the tenth plague arrives and every Egyptian firstborn male dies.  Pharaoh is panic-stricken, and changes his tune.  He now orders the Jews to leave Egypt.   The Jews leave Egypt in great haste, with loaves of unleavened bread (matzo) on their shoulders, and with great amounts of wealth in their sacks (given to them by the defeated Egyptians).  The Torah portion concludes with a series of Passover-related laws, the commandment to redeem the first-born child and to wear tefillin (phylacteries).